Wind turbine and device for protecting from lightning

Abstract

A device for protecting from lightning ( 30 ) is intended to form at least a portion of an external surface of a structure to be protected and comprises a ground plane ( 32 ), a dielectric substrate ( 34 ) arranged on the ground plane, and an array of first metal elements ( 36 ) arranged on the dielectric substrate ( 34 ) and extending substantially parallel to the ground plane ( 32 ) in such a way that any pair of consecutive elements from said first metal elements ( 36 ) is separated by a distance comprised between 0.01 millimetres and 10 millimetres, said first metal elements being distributed in juxtaposed similar patterns, each of said patterns including first metal elements of different dimensions corresponding respectively to different electromagnetic resonant frequencies the juxtaposition of which defines an electromagnetic absorption band of the pattern.

What is claimed is: 
     
       1. A wind turbine comprising:
 a rotor hub; 
 at least one blade supported by the rotor hub; and 
 an earth connection device through which lightning can be carried to the earth, 
 wherein the blade comprises an aerodynamic external skin, 
 wherein said aerodynamic external skin integrates at least one lightning protection device, and wherein said lightning protection device comprises; 
 a ground plane located on an inner side of the blade, 
 a dielectric substrate arranged on the ground plane, and 
 set of first metal elements arranged on the dielectric substrate and located on an outer side of the blade, 
 wherein the set of first metal elements extends substantially parallel to the ground plane in such a way that any pair of consecutive elements of said set of first metal elements is separated by a distance of between 0.01 millimeters and 10 millimeters, said first metal elements being distributed in juxtaposed similar patterns, each of said patterns including first metal elements with different dimensions corresponding to different electromagnetic resonant frequencies, the juxtaposition of which defines an electromagnetic absorption band of the pattern, and wherein first metal elements of said set of first metal elements located at one end of the lightning protection device facing the rotor hub are electrically connected to the earth connection device, and 
 said lighting protection device further comprising a metal grid formed from interlacing of metal strips formed on the dielectric substrate between first metal elements of said set of first metal elements. 
 
     
     
       2. The wind turbine according to  claim 1 , in which every pair of consecutive elements among said first metal elements of a same pattern is separated by a distance between 0.3 millimeters and 3 millimeters. 
     
     
       3. The wind turbine according to  claim 1 , in which said metal strips extend between said patterns. 
     
     
       4. The wind turbine according to  claim 1 , in which the ground plane is formed from a continuous metal grating. 
     
     
       5. The wind turbine according to  claim 1 , in which the ground plane is formed from a set of grating portions at a uniform spacing from each other. 
     
     
       6. The wind turbine according to  claim 1 , in which the ground plane is formed from a plurality of second metal elements at equal spacing from each other. 
     
     
       7. The wind turbine according to  claim 1 , wherein the metal grid is connected to the earth connection device. 
     
     
       8. The wind turbine according to  claim 4 , wherein the metal grating forming the ground plane is connected to the earth connection device.